The U.S. Department of Energy’s (DOE) Solar Decathlon has wound up in Washington, D.C. with Team Germany taking the top honors, followed by the University of Illinois at Urbana-Champaign in second place, and Team California taking out third. As we reported last week the competition to design, build, and operate the most attractive and efficient solar-powered home saw 20 university-led teams from around the world competing in ten contests, ranging from subjective elements such as architecture, market viability, communications, lighting design, and engineering, to technical measurements of how well the homes provided energy for space heating and cooling, hot water, home entertainment, appliances, and net metering.

Team Germany

The winning surPLUShome design is the second-straight Solar Decathlon victory for
Team Germany, who also took the honors in the previous competition in 2007. Their 2009 winning entry is essentially a two-story cube, which earned it the nickname the “Cube House.”


The cube shape of the house was chosen to provide maximum dimensions and surface area for the solar cells that almost totally cover the exterior: an 11.1-kW photovoltaic (PV) system made of 40 single-crystal silicon panels on the roof and about 250 thin-film copper indium gallium diselenide (CIGS) panels on the sides.

The CIGS panels are slightly less efficient than the silicon panels but, because they can produce energy from indirect sunlight, they perform better in cloudy weather and were also placed on the northern façade of the house, which is not exposed to direct sunlight. This proved beneficial as it enabled the house to produce a surplus of power, even during three days of rain.

To maintain comfortable interior temperatures, the façade includes highly insulating, custom vacuum insulation panels and phase-change material in the walls (paraffin) and ceiling (salt hydrate). Automated louver-covered windows were also used to block unwanted solar heat.


The surPLUShome was based on a single room concept with a multi-functional body containing the primary functions such as the kitchen, stairs and bathroom serving as its central element. The kitchen section of the multi-functional body is equipped with highly energy-efficient kitchen devices, as well as household appliances such as a washing machine and dryer, while the bathroom section contains a wash basin, shower and toilet.

The living area takes up the largest space in the surPLUShome, with a high ceiling and large southern-facing sliding door to let in light. The living area also serves as the sleeping area, with a either a single or double bed able to be pulled out from the bottom two steps of the central stairway.

How the race was won

The Net Metering contest to measure the houses’ consumption and production of energy was the most heavily weighted contest and Team Germany managed to score a perfect 150 points. They also took out the Comfort Zone contest with a score of 92 out of 100 points for maintaining indoor temperatures between 72 and 76 degrees Fahrenheit, and relative humidity between 40 percent and 55 percent.

Second placed University of Illinois at Urbana-Champaign’s Gable Home entry was designed to blend innovative technology and vernacular Midwestern architecture. It took out the Appliances contest, which was based on keeping a refrigerator and freezer cold, washing and drying 10 loads of laundry during the contest week, and washing dishes in a dishwasher five times during the competition – all on electricity generated only from sunlight.

The Gable Home was also the winner of the Home Entertainment contest, which required students to use electricity generated by their solar houses to run interior and exterior lights, a TV, a computer, and a kitchen appliance to boil water. It also required teams to hold two dinner parties and a movie night for neighbors. The Gable Home also earned the maximum number of points in the Hot Water contest’s “shower tests,” which aimed to deliver 15 gallons of water heated by the sun in ten minutes or less.

Team California’s Refract House came in third with first places in the Architecture and Communications contests. The Architecture contest was judged by a jury of architects who awarded points based on the aesthetic and functional elements of the homes’ designs. This included the ease of circulation among the public and private areas, the integration of various spaces into a holistic design, the generosity and sufficiency of space in the house, and the house’s design surprises meant to inspire visitors. Meanwhile, the Communications contest was judged by a jury of Web site and public relations experts looking at the communications efforts, including communications plans, student-led tours, and team Web site of the different teams.

Overall, Team Germany earned 908.29 points out of a possible 1,000 to win the competition, ahead of the University of Illinois at Urbana-Champaign with 897.30 points and Team California with 863.08 points.

The application process for the next Solar Decathlon, to be held in fall 2011, has already begun with Team Germany looking the team to beat as they attempt to make it a three-peat.

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